Two weeks ago, I penned an article on 81 bird species in North America becoming imperiled.

The Partners in Flight organization listed a number of factors, one of which hybridization.

So, what’s up here? One very threatened bird, especially in the Appalachians, including our area, is the golden-winged warbler. They seek out regrowing forests or shrub areas generally above 1,500 feet in elevation.

A very similar species, the blue-winged warbler, likes the same habitat but breeds in lower elevations. The theory proposed is that with slowly warming Earth temperatures, the blue-winged warbler is “moving farther up the mountains.” Before that happened, these birds seldom interacted; now they are interbreeding.

Let’s take a step back for a second. Hybrid animals result from the breeding of two different species or subspecies, most likely yielding offspring that can’t reproduce.

Mules are the offspring of a female horse and a male donkey. This breeding has been occurring since about 3000 BC, where people wanted a strong working animal, very durable, but not so obstinate as a donkey. Mules cannot mate and produce mules. A mule is a hybrid.

Another hybrid of which most anglers would be familiar is the tiger muskellunge. Tiger muskies have been raised by the Pennsylvania Fish and Boat Commission and many other states’ fish and game agencies.

The tiger muskellunge proved to grow faster and was more durable than both of its parents. Tiger muskies are produced with eggs from a female northern muskellunge and milt from a male northern pike. They proved to be excellent predators to control the populations of unwanted smaller fish species in lakes and are exciting fishing opportunities for anglers.

One of the chief reason this hybrid is stocked in lakes/rivers is that if it were to be a problem, the hybrid tiger musky is sterile, as are most other hybrids, and it would eventually disappear from that waterway. If they escaped/migrated somehow from that waterway, the same result occurs.

Regarding their rapid growth, about a month after my graduation from ESSC in 1975 I decided to fish the Beltzville shoreline for bass on the opening night of the season.

I didn’t catch a largemouth, but a 39-inch muskie. (The dam was completed and filled in 1972; imagine how fast the 12-inch muskies stocked there as the lake filled to be that large in about three years.)

The threatened golden-winged warbler is in trouble because even though it may breed and have young, if it bred with a blue-winged warbler (more common today) its young the next year will not produce any golden-winged warblers to replenish the populations.

Hybridization in nature can be a big problem. My guess that in years after my time on Earth, at least in the Appalachians, there will only be blue-winged warblers and no golden-winged because of hybridization.

Black duck numbers are dropping. The cause: Mallard ducks are breeding with black ducks and the resulting hybrid surprisingly is fertile. But seldom do these hybrid black duck/mallard crosses breed with a pure black duck. It is probable, in the future, that we would lose the true genetic black duck. Many black duck hybrids can be found today compared to a true black duck.

Test your outdoor knowledge: The mallard duck males have been documented having bred with ____ other duck species. A. 40; B. 25; C. 10; D. 5.

Last Week’s Trivia Answer: Bluebirds and tree swallows use grasses/pine needles to fashion their nests (tree swallows add many feathers) but only the robin uses mud and grass to form a cup-shaped nest. They also don’t nest in cavities/bird boxes as do the other two.

Email Barry Reed at breed71@gmail.com